They found that firing low temperature plasma beams at dentin -- the fibrous tooth structure beneath the enamel coating -- reduced the amount of dental bacteria by up to 10,000-fold. The results suggest that plasma jets could be used to remove infected tissue in tooth cavities, a procedure that currently requires a drill.

For the study, the researchers infected dentin from extracted human molars with four strains of bacteria and then exposed the dentin to plasma jets for 6, 12 or 18 seconds. The amount of bacteria that was eliminated increased the longer the dentin was exposed to the plasma jets.

The study is in the February issue of the Journal of Medical Microbiology.

"Drilling is a very uncomfortable and sometimes painful experience," the study's leader, Dr. Stefan Rupf, of Saarland University in Homburg, said in a news release from the journal's publisher. "Cold plasma, in contrast, is a completely contact-free method that is highly effective."

Rupf said that "huge progress" is being made in the field of plasma medicine and that "a clinical treatment for dental cavities can be expected within three to five years."